Cigarette smoking remains the number one cause of preventable morbidity and mortality in the U.S. Each year, one third to one half of smokers attempt to quit at least once; however, approximately 94% of quit attempts fail. A number of interventions have been developed to help smokers initiate and maintain abstinence. Unfortunately, even though most smokers express a desire to quit, relapse is the most likely outcome. Thus, it is not only critically important that more effective interventions be developed to reduce relapse, but it is also a primary public health goal to ensure that evidence-based smoking cessation interventions be made widely available, and at a low cost, to smokers. One of the most powerful, evidence-based behavioral interventions for smoking cessation is contingency management (CM). CM for smoking cessation consists of delivering incentives (typically money) contingent on objective evidence of smoking abstinence (e.g., carbon monoxide [CO] levels in the exhaled breath). However, the cost of providing incentives, the time it takes to administer the program, and the distance that must be traveled to participate in supervised monitoring procedures are often cited as barriers to CM. This SBIR Fast-Track proposal seeks to develop a mobile videogame-based contingency management intervention for smoking cessation. The goals of the present proposal are to markedly decrease costs, improve sustainability, and further increase accessibility of CM interventions for smoking cessation. To increase access, all aspects of the intervention will be available via Android or iOS smartphones used in conjunction with a matchbox-sized peripheral device for monitoring breath CO. To decrease costs and improve sustainability, the mobile game we will develop will allow us to replace the monetary incentives typically used in CM interventions with in-game virtual rewards that can immediately be used to help players meet game objectives, as well as with social reinforcement, prompted and incentivized in the context of the game. In Phase I, an iterative design and formative evaluation process will be used to create a game design and storyboard for the mobile game to be developed in Phase II, the CO data collection software will be produced and integrated with the CO Monitor, and a demo of the videogame will be developed. The demo created will be presented to 20 treatment-seeking smokers owning the target platform devices, who will then complete a survey & prospective evaluation of the planned intervention. In Phase II the development of the videogame, capable of supporting 7 weeks of play, will be completed, and a 7 week randomized control trial outcome evaluation will be conducted with 114 subjects to assess the feasibility, acceptability, appeal, and efficacy of the smoking cessation intervention.